High voltage devices, such as high voltage field-effect transistors, having high breakdown voltage and low on-state resistance are used in, for example, power management products. The performance of the high voltage transistors depends on the drain-to-source on-resistance (Rdson) as well as breakdown voltage (Vbr). For example, low Rdson results in high switching speed while high Vbr increases voltage capabilities. However, Rdson and Vbr of high voltage devices are typically inversely related. Thus, there is a tradeoff between Rdson and Vbr during performance optimizations. Increasing the high Vbr of high voltage devices may sometimes undesirably lead to an increase in external resistance (Rext). The increase of Rext, however, degrades the performance of the high voltage device.
Accordingly, there is a need to provide improved high voltage devices which have low Rdson as well as high Vbr. Moreover, there is also a desire to provide simplified and cost effective methods to form these high voltage devices.